Terminal



June 9, 1942'. w. v. JOHNSON 2,286,097

TERMINAL Filed Oct. 29, 1958 Fig. 4.

1a? 6 12mg 7/ 90x15 ZZ WITNESSES: INVENTOR Welzon V Jo son. 06 BY ATT EYPatented June 9, 1%42 TERMINAL Welton V. Johnson, Short Hills, N. J.,assignor to Westinghouse Electric & Manufacturing Company, EastPittsburgh, Pa., a corporation of Pennsylvania Application October 29,1938, Serial No. 237,772

2 Claims.

This invention relates to terminals and it has particular relation toeye or loop terminals for electrical conductors or leads employed forconnecting instruments and electrical circuits.

Terminals heretofore employed in practice ordinarily comprise a metalliclug which is united to an electrical conductor by means of solder. Suchterminals have a number of objections resulting from their construction.Because of the heat required during the soldering operation, insulationpresent on the conductor may be charred and destroyed, and the metalitself of the conductor or terminal may be rendered more brittle.Furthermore, the eifectiveness of the bond between the terminal and theconductor is dependent upon the skill of the operator and accordingly isextremely variable. -In order to insulate such terminals, it has beenthe practice to employ three separate pieces of insulation which add tothe complexity of manufacture and detract from the appearance of thefinished terminal. After the completion of the soldering operation, theexcess flux and solder, of course, must be removed. Finally, themechanical strength of the bond between the terminal and the conductoris relatively low.

In accordance with this invention, a terminal is provided for aconductor by slipping over the end of the conductor a snugly fittedsheath which is bent together with a portion of the conductor enclosedtherein into an eye or loop to form a finished terminal. Although theterminal could be used without further modification, I prefer to flattenthe eye or loop by subjecting it to a pressing operation which not onlyproduces an excellent bond between the internal surface of the sheathand the portion of the conductor adjacent thereto, but also provides aflat external surface on each side of the loop or eye which makes asatisfactory electrical contact with a terminal screw on which theterminal is mounted or with adjacent terminals in case a number ofterminals are mounted on the same terminal screw. Insulation of theterminal assembly may be efiected by slipping over the conductor atubular insulation member, such as that commonly referred to asspaghetti, which may be extended over an end of the terminal sheath.

It is, therefore, an object of this invention to provide a terminalwhich may be mounted in final position without employing a binder.

It is another object of this invention to provide a tubular sheath forthe end of the conductor which has a flattened loop portion.

It is another object of this invention to insulate a terminal assemblyby extending over an end of the terminal and an associated conductor atubular insulating member.

It is a further object of this invention to provide a conductor terminalsheath having a flared end for facilitating entry of the conductortherein It is a still further object of this invention to provide aconductor terminal sheath having a partially or completely closed end.

It is another object of this invention to provide an improved method forconstructing terminals having the characteristics set forth in thepreceding objects.

Other objects of this invention will be apparent from the followingdescription taken in conjunction with the accompanying drawing, inwhich:

Figure l is a view in plan of a lead employing terminals constructed inaccordance with this invention; and

Figs. 2, 3 and 4 are detail views showing various stages of themanufacture of the finished terminals illustrated in Fig. 1.

Referring to the drawing, Fig. 1 shows a lead comprising a conductor I,which is illustrated as a stranded, flexible conductor, although otherconductors, such as solid conductors, may be employed. The conductor lis provided with a terminal A having a neck portion 2 and a loop or eyeportion 3. As illustrated, the neck portion 2 is circular incross-section, whereas the loop or eye portion 3 has a flattened surface4. Insulation for the assembly is provided by a tubular insulation 5,such as that commonly designated as spaghetti, but it is to beunderstood that my invention may be applied to pre-insulated conductors.

The terminalA shown in Fig. 1 is constructed by forming a tubular sleeveor sheath 6, as illustrated in Fig. 2. This sheath may be constructed innumerous ways, but preferably it is a seamless tube ofelectro-conductive material, such as copper. ,This sheath may beemployed without further modification, but for purposes hereinafter setforth it is preferred to flare one end 1 outwardly and to close, eitherpartially or completely, a second end 8. This may be done in anysuitable manner, as by peening or spinning the metal at each end intothe desired shape. In the specific embodiment illustrated, the end 8 isonly partially closed.

The sheath as thus far described is next slipped over a conductor Iauntil the conductor substantially abuts the closed end 8 of the sheath.Preferably, the sheath is of a diameter such that it snugly receives theconductor la. Because of the flare on the open end I of the sheath, theconductors la may be readily guided into the sheath. When the conductorla has been introduced into the sheath, the sheath and the enclosedconductor are bent into the form of a loop 3a, as clearly illustrated inFig. 3. If desired, the terminal assembly may be considered as completedat this stage, but the terminals so constructed are not entirelysatisfactory. Although a fair contact is provided between the conductorIa and the sheath, this contact is not as satisfactory and permanent asdesired. Moreover, since the sheath has a circular cross-section radialfrom the axis of the eye or loop, it offers what is substantially a linecontact to the terminal screw or to adjacent terminals if more than oneterminal is mounted on the same screw, as is customary in relay andother electrical work. When several terminals are mounted on the sameterminal screw, because of the line contacts therebetween the terminalstend to stack irregularly, and when the terminal screw is tightened, thepressure exterted thereby on the stacked terminals may force the eyes orloops of the terminals open with a resultant possibility of a terminaldropping completely away from the terminal screw. Moreover, theadherence between the conductor la and the sheath at the stageillustrated in Fig. 3 is not sufficient to assure the retention of theconductor in the sheath under stresses ordinarily encountered inpractice. That is, if a tension is applied to the conductor la, theconductor may be withdrawn entirely from the sheath.

The various defects pointed out in the foregoing paragraph may beovercome by subjecting the eye or loop 3a to pressure sufficient toflatten opposite surfaces thereof. This pressure may be applied innumerous ways, but in the particular manner illustrated in Fig. 4, theeye 3a is placed between a pair of dies 9, I9. The lower die I isprovided with a pocket having a wall H which substantially surrounds theeye in order to prevent the eye from opening under the high pressuresemployed. If desired, the die I0 may also be provided with a coreextending into the opening of the eye in order to prevent an excessivecontraction of the opening. The opposed faces of the die may be givenany desirable configuration, but ordinarily I prefer to make the portionextending over the eye or loop 3a substantially flat with slightlyrounded edges l2, l3 for merging the flattened portion of the eye orloop 3a gradually into the circular neck portion 2a of the terminal.

Under the influence of the high pressures exerted by the dies 9, 1!],the internal surface of the sheath is forced against the conductor Iaflattening the conductor and forming an excellent electrical contacttherewith. Moreover, the flattening operation tends to increase thestrength of the loop or eye 3a in a direction radial from the axisthereof, thereby tending to restrain the loop or eye from opening underthe influence of the pressure exerted by the terminal screw employed forattaching the terminal in its desired position. The compacting of theconductor la in the sheath also increases the mechanical adherencetherebetween, which lessens the possibilities of the conductor beingpulled away from the sheath under the forces experienced in practice.

Several advantages accrue from the particular shape given the terminal.Because of the flat surfaces imparted to the terminal by the dies, anumber of these terminals may be stacked on a terminal screw and willstack neatly and uniformly. This is a very important advantage in manyapplications, such as relay work, in which a number of terminals must bemounted on the same terminal screw. Because of the large flat surfacesprovided, excellent electrical contact, as well as mechanical contact,is provided between adjacent surfaces of the terminals and between theterminals and the terminal screw. The closed or partially closed end 8of the sheath not only acts as a stop for the conductor when it isinitially inserted in the sheath, but it prevents fraying of the end ofthe conductor under the pressure of the dies 9, l0 and provides a neatappearance for the resulting terminal. The flare formed at the end I ofthe sheath, as above noted, serves as a guide for the conductor la whenit is initially introduced into the sheath and thereafter serves as aguide to prevent abrupt bending and nicking of the conductor la.Preferably, the edge of the end I is rounded to preclude any possibilityof cutting the insulation. Since no solder is employed in the terminal,the terminal may be employed in apparatus subjected to high heat withoutfear of failure.

In order to insulate the conductor and terminal illustrated in Fig. 4,it is merely necessary to slip a tubular insulating member over theconductor I a and neck 2a of the terminal to produce the final leadillustrated in Fig. 1. The one-piece insulation serves to stiffensomewhat the junction between the conductor Ia and the neck 2a of theterminal, and may be extended until it abuts the eye or loop of theterminal.

As stated above, any suitable material may be employed for the sheath 6,copper and brass being examples of suitable electro-conductive metalsfor this purpose. In any event the material employed should be one thatmay be deformed under pressure and that will retain the deformed shape.

If a terminal is desired at each end of the conductor I, it is easy tofit a second sheath B over the remaining end of the conductor, a portionof the sheath being introduced between the conductor I and theinsulation 5. This sheath is then bent into an eye or loop and pressedbetween the dies 9, I!) in the same manner described with reference tothe terminal A.

The operation .of my invention may be recapitulated briefly as follows:In order to form a terminal for a conductor, a sheath 6 is selectedhaving an internal diameter of a size sufficient to receive snugly aconductor. One end of the sheath 6 is provided with a slight outwardflare in order to act as a guide for the conductor, and the other end ofthesheath is partially or completely closed to'form a stop for theconductor and to prevent fraying of the conductor ends during subsequenttreatment. After a conductor has been inserted into the sheath, thesheath is bent into the form of an eye or loop, and the eye or loop issub jected to high pressures in order to flatten opposed surfaces and toimprove the electrical and mechanical contacts between the sheath andthe conductor enclosed thereby. Finally, an insulating member is slippedover the conductor and a neck left on the terminal.

Although I have described my invention with reference to certain.specific embodiments thereof, it is obvious that numerous modificationsthereof are possible. Therefore, I do not wish my invention to berestricted except as required by the appended claims when interpreted inview of the prior art.

I claim as my invention:

1. The method for mounting a tubular sheath terminal on a flexibleconductor which comprises placing said sheath terminal over the end ofsaid conductor, bending said sheath terminal and enclosed end of saidconductor into the configuration of a loop, maintaining a guide deviceabout said loop for preventing opening thereof, and flattening saidsheath terminal and enclosed end under pressure over a substantial partof the width of said sheath for forcing opposed flattened surfaces ofsaid sheath terminal into intimate contact with said conductor whileretaining substantially said loop configuration, said flattening of saidsheath serving to form opposed flattened surfaces on said loop extendingin planes substantially transverse to the axis of said loop andproportioned with said sheath for resisting opening of said loop underthe influence of terminal screw pressure applied thereto.

2. The method for mounting a tubular sheath on a flexible conductorwhich comprises partially closing a first end of said sheath, flaringoutwardly the walls of said sheath at a second end of said sheath,inserting said conductor through said second end until said conductorsubstantially abuts said first end, bending said sheath and enclosedconductor into the configuration of a loop, maintaining a guide deviceabout said loop for preventing opening thereof, and pressing said loopbetween fiat surfaces with sufiicient pressure to produce opposedsubstantial flat surfaces thereon and to force said sheath into intimatecontact with said enclosed conductor, said pressing of said sheathserving to form opposed fiat surfaces on said loop extendingsubstantially radially from the axis of the loop and proportioned withsaid sheath for resisting opening of said loop under the influence ofterminal screw pressure applied thereto.

WELTON V. JOHNSON.

